sched: clean up wakeup balancing, rename variables

rename 'cpu' to 'prev_cpu'. No code changed:

kernel/sched.o:

   text	   data	    bss	    dec	    hex	filename
  42521	   2858	    232	  45611	   b22b	sched.o.before
  42521	   2858	    232	  45611	   b22b	sched.o.after

md5:
   09b31c44e9aff8666f72773dc433e2df  sched.o.before.asm
   09b31c44e9aff8666f72773dc433e2df  sched.o.after.asm

Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 70679b2..2d2be02 100644 (file)
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -983,7 +983,7 @@ static inline int wake_idle(int cpu, struct task_struct *p)
 
 static int
 wake_affine(struct rq *rq, struct sched_domain *this_sd, struct task_struct *p,
-           int cpu, int this_cpu, int sync, int idx,
+           int prev_cpu, int this_cpu, int sync, int idx,
            unsigned long load, unsigned long this_load,
            unsigned int imbalance)
 {
@@ -1010,7 +1010,7 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct task_struct *p,
        if (sync)
                tl -= current->se.load.weight;
 
-       if ((tl <= load && tl + target_load(cpu, idx) <= tl_per_task) ||
+       if ((tl <= load && tl + target_load(prev_cpu, idx) <= tl_per_task) ||
                        100*(tl + p->se.load.weight) <= imbalance*load) {
                /*
                 * This domain has SD_WAKE_AFFINE and
@@ -1028,22 +1028,26 @@ wake_affine(struct rq *rq, struct sched_domain *this_sd, struct task_struct *p,
 static int select_task_rq_fair(struct task_struct *p, int sync)
 {
        struct sched_domain *sd, *this_sd = NULL;
+       int prev_cpu, this_cpu, new_cpu;
        unsigned long load, this_load;
-       int cpu, this_cpu, new_cpu;
        unsigned int imbalance;
        struct rq *rq;
        int idx;
 
-       cpu      = task_cpu(p);
-       rq       = task_rq(p);
-       this_cpu = smp_processor_id();
-       new_cpu  = cpu;
+       prev_cpu        = task_cpu(p);
+       rq              = task_rq(p);
+       this_cpu        = smp_processor_id();
+       new_cpu         = prev_cpu;
 
-       if (cpu == this_cpu)
+       if (prev_cpu == this_cpu)
                goto out_set_cpu;
 
+       /*
+        * 'this_sd' is the first domain that both
+        * this_cpu and prev_cpu are present in:
+        */
        for_each_domain(this_cpu, sd) {
-               if (cpu_isset(cpu, sd->span)) {
+               if (cpu_isset(prev_cpu, sd->span)) {
                        this_sd = sd;
                        break;
                }
@@ -1062,12 +1066,12 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
 
        imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
 
-       load = source_load(cpu, idx);
+       load = source_load(prev_cpu, idx);
        this_load = target_load(this_cpu, idx);
 
        new_cpu = this_cpu; /* Wake to this CPU if we can */
 
-       if (wake_affine(rq, this_sd, p, cpu, this_cpu, sync, idx,
+       if (wake_affine(rq, this_sd, p, prev_cpu, this_cpu, sync, idx,
                                     load, this_load, imbalance))
                goto out_set_cpu;
 
@@ -1084,7 +1088,11 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
        }
 
 out_keep_cpu:
-       new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
+       /*
+        * Could not wake to this_cpu.
+        * Wake to the previous cpu instead:
+        */
+       new_cpu = prev_cpu;
 out_set_cpu:
        return wake_idle(new_cpu, p);
 }